Abstract
Many researchers have assumed that punishment evolved as a behavior-modification strategy, i.e. that it evolved because of the benefits resulting from the punishees modifying their behavior. In this article, however, we describe two alternative mechanisms for the evolution of punishment: punishment as a loss-cutting strategy (punishers avoid further exploitation by punishees) and punishment as a cost-imposing strategy (punishers impair the violator’s capacity to harm the punisher or its genetic relatives). Through reviewing many examples of punishment in a wide range of taxa, we show that punishment is common among plant and animal species and that the two mechanisms we describe have often been important for the evolution of punishment.